> -----Original Message-----
> From: Axel Lin [mailto:[email protected]]
> Sent: Thursday, March 27, 2014 8:46 AM
> To: Mark Brown
> Cc: Yang, Wenyou; linux-spi
> Subject: Re: [PATCH] spi: atmel: Fix test unsigned var < 0
>
> 2014-03-27 0:51 GMT+08:00 Mark Brown <[email protected]>:
> > On Sat, Mar 22, 2014 at 10:33:29PM +0800, Axel Lin wrote:
> >> current_remaining_bytes is an unsigned long and cannot be below 0.
> >
> >> - if (xfer->bits_per_word > 8) {
> >> +
> >> + if (xfer->bits_per_word > 8)
> >> as->current_remaining_bytes -= 2;
> >> - if (as->current_remaining_bytes < 0)
> >> - as->current_remaining_bytes = 0;
> >> - } else {
> >> + else
> >> as->current_remaining_bytes--;
> >> - }
> >
> > This removes an error check in the case that we set the remaining
> > bytes to -1. The length validation the core does should ensure that
> > never happens but it seems wrong to just ignore that - we should at
> > least note in the changelog that the analysis has been done.
> I thought it never happen and there is no bug report for this so it's
> safe with this patch.
>
> >
> > Are you sure that the best fix isn't to just use an int here?
> Wenyou,
> Any comments for this?
Like Mark said, It seems it is more reasonable using a signed int, instead of
unsigned int.
-->8 ---
diff --git a/drivers/spi/spi-atmel.c b/drivers/spi/spi-atmel.c
index 8005f98..485e6cc 100644
--- a/drivers/spi/spi-atmel.c
+++ b/drivers/spi/spi-atmel.c
@@ -224,7 +224,7 @@ struct atmel_spi {
struct platform_device *pdev;
struct spi_transfer *current_transfer;
- unsigned long current_remaining_bytes;
+ int current_remaining_bytes;
int done_status;
struct completion xfer_completion;
@@ -1110,6 +1110,8 @@ static int atmel_spi_one_transfer(struct spi_master
*master,
atmel_spi_next_xfer_pio(master, xfer);
} else {
as->current_remaining_bytes -= len;
+ if (as->current_remaining_bytes < 0)
+ as->current_remaining_bytes = 0;
}
} else {
atmel_spi_next_xfer_pio(master, xfer);
--<8 ---
Best Regards,
Wenyou Yang
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